[clang] Delay checking of -fopenmp-host-ir-file-path

[jansvoboda11]

This PR is part of an effort to remove file system usage from the command line parsing code. The reason for that is that it's impossible to do file system access correctly without a configured VFS, and the VFS can only be configured after the command line is parsed. I don't want to intertwine command line parsing and VFS configuration, so I decided to perform the file system access after the command line is parsed and the VFS is configured - ideally right before the file system entity is used for the first time.

This patch delays opening the OpenMP host IR file until codegen.

[llvmbot]

@llvm/pr-subscribers-clang-codegen

@llvm/pr-subscribers-clang

Author: Jan Svoboda (jansvoboda11)

Changes

This PR is part of an effort to remove file system usage from the command line parsing code. The reason for that is that it's impossible to do file system access correctly without a configured VFS, and the VFS can only be configured after the command line is parsed. I don't want to intertwine command line parsing and VFS configuration, so I decided to perform the file system access after the command line is parsed and the VFS is configured - ideally right before the file system entity is used for the first time.

This patch delays opening the OpenMP host IR file until codegen.

---

Full diff: https://github.com/llvm/llvm-project/pull/150124.diff

5 Files Affected:

• (modified) clang/include/clang/Basic/DiagnosticDriverKinds.td (-3)
• (modified) clang/include/clang/Basic/DiagnosticFrontendKinds.td (+3)
• (modified) clang/include/clang/Driver/Options.td (+2-1)
• (modified) clang/lib/CodeGen/CodeGenModule.cpp (+4)
• (modified) clang/lib/Frontend/CompilerInvocation.cpp (-12)

diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 759ba0419bd45..fbb8e68f6ed12 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -361,9 +361,6 @@ def err_drv_optimization_remark_format : Error<
 def err_drv_no_neon_modifier : Error<"[no]neon is not accepted as modifier, please use [no]simd instead">;
 def err_drv_invalid_omp_target : Error<"OpenMP target is invalid: '%0'">;
 def err_drv_incompatible_omp_arch : Error<"OpenMP target architecture '%0' pointer size is incompatible with host '%1'">;
-def err_drv_omp_host_ir_file_not_found : Error<
-  "provided host compiler IR file '%0' is required to generate code for OpenMP "
-  "target regions but cannot be found">;
 def err_drv_omp_host_target_not_supported : Error<
   "target '%0' is not a supported OpenMP host target">;
 def err_drv_expecting_fopenmp_with_fopenmp_targets : Error<
diff --git a/clang/include/clang/Basic/DiagnosticFrontendKinds.td b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
index 8a8db27490f06..f988c7a5969c6 100644
--- a/clang/include/clang/Basic/DiagnosticFrontendKinds.td
+++ b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -308,6 +308,9 @@ def err_target_unsupported_type_for_abi
     : Error<"%0 requires %1 type support, but ABI '%2' does not support it">;
 }
 
+def err_omp_host_ir_file_not_found : Error<
+  "provided host compiler IR file '%0' is required to generate code for OpenMP "
+  "target regions but cannot be found">;
 def err_alias_to_undefined : Error<
   "%select{alias|ifunc}0 must point to a defined "
   "%select{variable or |}1function">;
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 97b2eb9c44a88..b15da41f822b1 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -8645,7 +8645,8 @@ def fopenmp_is_target_device : Flag<["-"], "fopenmp-is-target-device">,
   HelpText<"Generate code only for an OpenMP target device.">;
 def : Flag<["-"], "fopenmp-is-device">, Alias<fopenmp_is_target_device>;
 def fopenmp_host_ir_file_path : Separate<["-"], "fopenmp-host-ir-file-path">,
-  HelpText<"Path to the IR file produced by the frontend for the host.">;
+  HelpText<"Path to the IR file produced by the frontend for the host.">,
+  MarshallingInfoString<LangOpts<"OMPHostIRFile">>;
 
 } // let Visibility = [CC1Option, FC1Option]
 
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 236cc3d9e8907..8362c658ad888 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -582,6 +582,10 @@ void CodeGenModule::createOpenCLRuntime() {
 }
 
 void CodeGenModule::createOpenMPRuntime() {
+  if (!LangOpts.OMPHostIRFile.empty() && !FS->exists(LangOpts.OMPHostIRFile))
+    Diags.Report(diag::err_omp_host_ir_file_not_found)
+        << LangOpts.OMPHostIRFile;
+
   // Select a specialized code generation class based on the target, if any.
   // If it does not exist use the default implementation.
   switch (getTriple().getArch()) {
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 3a36250da57a3..1566ca626c560 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -3907,9 +3907,6 @@ void CompilerInvocationBase::GenerateLangArgs(const LangOptions &Opts,
     GenerateArg(Consumer, OPT_offload_targets_EQ, Targets);
   }
 
-  if (!Opts.OMPHostIRFile.empty())
-    GenerateArg(Consumer, OPT_fopenmp_host_ir_file_path, Opts.OMPHostIRFile);
-
   if (Opts.OpenMPCUDAMode)
     GenerateArg(Consumer, OPT_fopenmp_cuda_mode);
 
@@ -4405,15 +4402,6 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
     }
   }
 
-  // Get OpenMP host file path if any and report if a non existent file is
-  // found
-  if (Arg *A = Args.getLastArg(options::OPT_fopenmp_host_ir_file_path)) {
-    Opts.OMPHostIRFile = A->getValue();
-    if (!llvm::sys::fs::exists(Opts.OMPHostIRFile))
-      Diags.Report(diag::err_drv_omp_host_ir_file_not_found)
-          << Opts.OMPHostIRFile;
-  }
-
   // Set CUDA mode for OpenMP target NVPTX/AMDGCN if specified in options
   Opts.OpenMPCUDAMode = Opts.OpenMPIsTargetDevice &&
                         (T.isNVPTX() || T.isAMDGCN()) &&

[benlangmuir]

LGTM. Ideally we should have a test that you can VFS map this file